Furnace efficiency meter



Oct. 2, 19,28.` Ll

J. M. sPiTzGLAssg FURNACE EFFIC' ENGY METER Filed dan. 12, 1927 if INVEN TOR.

A TTORNEYJ laten'ted Oct. 2, 1928.;

UNITED STATES PATENT OFFICE- JACOB M. SPITZGLASS, OF CIIICAGO, ILLINOIS,ASSIGNOR TO REPUBLIC FLOW METERS COMPANY, OF CHICAGO, ILLINOIS, ACORPORATION OF ILLINOIS.

FURNACE EFFICIENCY METER.

Original application led May 1, 1926, Serial No, 105,957. Divided andthis application led January 12,

1927. Serial No. 160,721.

This application is a division of my pending 'application Serial#105.957, filed May lst, 1926, and relates especially to the apparatusshown vin said pending application. One object of the present inventionis to provide means by which the operator may at all itimes be appraisedof the conditions existing in the apparatus so that if he observes thatany of them are at varia-nce with those which have been predetermined asbeing most advantageous, they may be corrected, thus causing theapparatus always to function with maximum leli'iciency even though thecapacities at which it is operating change from time to time. Forillustration, taken the case of i a steam generating plant in which fuelis Q employed to generate the heat, Ordinarily upon the amount of powerrequired, or in the case of a heating plant. on the amount of heat whichmust be supplied. This factor of steam How, therefore, while vaniable,is not, practi-` cally speaking, under the control of the man in chargeofthe boiler room but is'dependent upon exigencies beyond his control,such as power or heat requirements. Consequently, the steam iiow orboiler capacity isl the given or predetermined factor.- and one purposeof i the invention is to provide a method and means for keeping theoperator advised as to the capacity at which the boiler is operating andalso keep him advised as to other lcorrelative conditions or factors sothat he may be able to modify them in such manner as to obtain maximumeiiiciency. Another object of the invention is to provide means by whichthe operator may readily compute the eiiiciency at which the boiler isoperating at any given moment. Another object is 'to provide means bywhich a permanent record of the various conditions or factors may hemade and the efficiency computed. f

Boiler eliciency is obtained in practice'by determining the loss of heatdue to improper combustion of fuel in the furnace and improperabsorption of heat in the boiler.

In ordinary boiler room operation most of the loss is the heat carriedaway through the stack by the heated gases. Improper comn -cative of thetotal loss of heat through the Let L signify the percent loss in theboiler, and W and T the weight and temperature lof the escaping gasesrespectively.

Then

` L=K`WT (l) K being a constant determined by the conditions of eachgiven case.

Of the twoy variables involved in the heat loss, T can be obtaineddirectly by measuring the temperature of the gases. Properly speaking,the temperature that should be oonsidered is the diiference between theroomyroom temperature and T will therefore be understood as representingthe diiference in temperature or the rise above room temperature. 1

- The value of W cannot be obtained directly but it has been found byexperience based on.I

numerous tests and experiments that the per? cent of carbon dioxide inthe. flue lgases isaidirect index of the'amount of air used [for y. thecombustion of the fuel l (it heilig under- -stood of course7 that in thepractical operation of a steam boiler a greater amount'ofair than thattheoretically required for complete combustion is always supplied., suchexcess resulting in the proportionate reduction of the CO2 contents inthe flue gases). Consequentl the amount of CO2 in the gases indicates te weight ofthe gases passing through the stack per pound of fuel. HenceWe may Write W=f/P ci simplified by substituting for KW, thissubstitution being close enough for practical purposes although in theactual construction of my apparatus the scale may be made according tothe more accurate y determined relation of W to P. j

Making the substitution in Equation (l) we have L=Kf (e) To illustratethe application of this equation; let it be assumed that a. given fuel,say western bituminous screenings, having a heat value of 11,000 B. t.u. per pounds, re'quires a. minimum Weight of 8.4 pounds of air perpound of fuel for perfect combustion result ingl in a maximum of 18.4per cent of-COz.

In practice. it is first necessary to obtain the characteristics of theparticular boiler for which the instrument is to he used and for thispurpose a test is run on the performance of the boiler. Let is bevassumed that the test shows 'that when T is equal to 500 de-V grees F.,and P is equal to 1Q percent CO2, the

. boiler has an overall eiiiciencyof 64 percent.

Subtractin this eiciency from 100 ercent` it is found; that L, the loss,isequa to 36 percent.

With a knowledge of these conditions solve for the value of K from"riiquationv 3),.A

For convenience we let T represent units of temperature, 100 degrees F.each. Then Thus the loss may be'computed at any' time by observing thetemperature and the percent of CO2 and this formula will holdsubstantially 'true for various capacities or rates of steam iiow of theparticular installation under observation.

To give a concrete illustration of the method and operation of theapparatus, reference may be had to the accompanying diagram in which arecord strip a is caused to travel beneath styli b, e, and d. In thepresent case, the strip is assumed to travel downward and as mechanismfor causing record strips to travel are Well known such mechanism neednot be described here. The sheet has cross rulings e which indicate thevarious hours of the day, these hours being denoted by appropriatemarkings f here shown in a column at the left margin of the strip. Thestrip is divided into three sections arranged side by side, the sectiono at the left representing steam iloiv, the section h at the middlerepresenting' the percent of CO2 and the section j at the rightrepresenting the stack temperature, or more properly speaking, thediffer Yence ,between the stack temperature and the temperature of theboiler room. l The steam ow section g has vertical rulngs'or ordinates7c spaced equally and'repre-` senting units of steam flow.. "These unitsare indicated .by a row'of numerals m which in the present illust-rationprogress from left to rightl in increments of ten. These units areselected arbitrarily and thel operator may, if he wishes, translatethese units into actual pounds of steam generated per hour.

The C()2 section iz, has vertical rulings or ordinates n spaced equallyand representing the percentage of CO2. These percentages are indicatedby a row of'numerals pwhich in the present .illustration progress fromleft to right in increments of two.

The stack temperature section y' at the right `has vertical rulings rthat are spaced equally and represent stack temperatures.. Thesetemperatures are indicated by a row of numerals 8j which progress fromleft'to right in increments of'one hundred. 'u Said roWsm,-p and s ofnumerals may be 4'printed directly upon the record strip at intervalsorthey may marked on a stationary portion of the apparatus in suchposition that the vertical lines or ordinates 7c, n, r will pass underthem in juxtaposition thereto.

Thestyli b, c, d may besupported and operated by any appropriate typeoflmechanism so long as they are movedin accord.

ance with the variation of the factors which they re resent. In thepresent case, which is large y diagrammatic, the styli are sup.-ported'upon rods t slidable upon a guide bar u and controlled by rodsa',y, e which are moved by suitable devices in accordance with the variablefactors of steam flow, percentage .of COzfand stack temperature. For.example', the'rcd a: may be operated by a steam lovvnieter, which is aknown instrument` and the rod g/ may be operated by agas analyzer I. it

ficiency greatest in proportion as the graph` C moves toward the rightand the graph D moves toward the left. Thus :by merely noting thepositions of the graphs or Styli 4 with respect to the line of referenceR, which igor other transparent material, although this is at the 'rightend of scale p and the left end of scale a, an approximate idea of theloss may be obtained. In other words, as the right end of scale p andthe lett end of scale s are coincident, an approximation mayf beobtained by noting-the dist-ance between p times ofthe actual conditionsof operation,

the two graphs. I

But my device in its developed forni goes further than this and is soconstructed thatthe observer may vby making a simple multi plication oftwo numerals calculate the eftr,`l

cieney at which the boiler is operating. The

mechanism `more intimately concerned with` `this characteristic will nowbe described; lThe bridge 'v is -mounted in front of the ."record stripand held stationary by screws c" `0r other suitable fastening means. Inthe -form illustrated it consists of g1ass,eelluloid .'f 'fis notessential. On this bridge in juxtaposif'ftration vrun from() to 9,progress from left t0 right, and eachunit represents 100 degrees bistacktemperature. This scale represents the 'temperature factor-T ofVEquation No.

(3) and it will be noted that it progresses in fthesaine direction asthe scales and that the 1 tion to scales there is marked a4 scales in`which thenumerals representunits of teun perature. .The ,integers inthepresent illus- 'zero point is aline R.

. -On the bridge ein juxtaposition to scale.

p there is marked a. scale p' in which the numerals vprogress -in theopposite direction g ner that the factor W'bears to thefactor P as'hereinabove explained. The scale p -in reality represents the W factor,although as. this is determined according to my method' from tlie'CO2factor in the flue gases, in thel l the CO2 indicator moves toward thetempera.-

from scalep.- lThese numerals are marked No( `(a)1f-fratethe mit p'betas; manip-ms cal relation tothe scale p in the same manparlance ofthe boiler room the scale p is more apt to be referred to as the CO2factor and is .-so marked in the diagram. In the From the foregoing itwill be evident that '.'5 the device illustrated'constitutes a boilereficiency meter and embodies in a single instrument means for indicating"or recording' three variable factors, viz, steam flow,.stack`temperature and percentage of the carbon dioxide in the staekgases, thelatter factor 1in my device `being interpretable in 'terms of the weightof iiue gases per pound of fuel. Thus the operator may be appraised atall and he is atforded simple and reliable means by which lie may, by aneasy computation, lcalculate the yeiiicieney at which the boiler isoperating. i' i v 'According to the arrangement illustrated, 90 thegraphs C and D approach each other as the eiiicie-ney inerease'sandrecede from each vother 'as it decreasegbutcitfwill be understood, ofcourse,v thatthis arrangement may be reversed without departing from thespirit '95 of the invention, for by reversing the scales p", sandreversingthe movement of the indicators c and Z the eicieney will begreatest when the graphs C, D are farthest apart and `leastwhen theyareeclosest together. The A. 'present arrangement, however, lispreferred, L for according-to 'it the, zerolocated ona common line (in tpoints may be .line R) and theinstrument will present a more graphic andreadily understood picture I in the mind 'ofthe operator.

The words stack gases in the specifica-` tion and the claims areintended and will be understood to mean the products of combustionwhether before or after they enter the' 110 stack proper.

I claim :M

l. A furnace efficiency meter comprising an u v indicator movable inaccordance with the temperatureo'f the stack gasesand an indicator 115movable in accordance with the percentage l of. carbon dioxide in thestack gases, said in- 1 dica-tors being so .positioned that the temper-`ature indicator moves'away from the CO2 lindicator as t-he temperaturesincrease and toward it as the temperatures decrease and increase, andmeans `for indicating the indie'present case vidual distances of saidindicators 'from a common reference point located between them. l.

3. AY furnace eliicienc-y meter having indicated thereon a basev pointof reference, an indicator movable toward' and from said -base point inproportion to the temperature ofthe stack gases, and a secondindicatormovable toward and from said base point in proportion to the Weight ofthe flue gases per'pound of fuel passing through the stack.

4. A furnace etiiciency meter comprising an indicator movable inproportion to the temperature of the stack gases, an indicator movablein proportion to the percentage of carbon dioxideV in the stack gases,and a scale in juxtaposition to the last mentioned indicator andreversed with respect to the movement thereof whereby the indicator willshow an increased value on the scale as the percentage of carbon dioxidedecreases and adecreased value as the percentage increases.

5. A furnace efficiency meter comprising an indicator movable inproportion to the percentage of carbon dioxide in the stack gases, and ascale of factors in juxtaposition to said indicator and reversed withrespect to the two.scales,-one reading directly in proportion to thetemperature of the stack gases, and the other reading inverselyproportional to the percentage of carbon dioxide in the flue gases, anindicator co-operating with the temperature scale and movable directlyproportional to the temperature ofA the stack gases, and a secondindicator co-operating with the second scale and movable in directproportion to the percentage of carbon dioxide in the flue gases, saidscales being in line with each other and coordinated, whereby 'bymultiplying the two readings the product will equal the loss ofefficiency of operation of the boiler. i

In testimony whereof, I atix my signature.

JACG'B M. SPITZGLASS.

